Profibus System Integration PDF 4.03MB - Schneider Electric

R/Wcommands 1HMI variables &Parameters to adjustExchanges tablePLC Master231) R/W commandsThese commands start the threshold read or write. These commands are exclusive.2) HMI variables & Parameters to adjustThe 2 first parameters define the slave address and the slot of the measurementbeing taken. This structure is divided into 2 parts: the parameters index and thevariable to be exchanged with the associated Genies (see SCADA Design).3) MailboxThe DP master uses a protocol called “Mailbox Messaging” to exchange parameterdata between the processor, the master and the slaves. The processor writes acommand into the Mailbox Out and the master executes the command. The responseis stored in Mailbox In.4) Exchange statusThis data provides the operation status.The screen shot below represents the DDT structure of this block.51